\section*{Acknowledgment}
This work has been partially supported by the Labex ACTION project (contract
-``ANR-11-LABX-01-01''). Computations have been performed on the Grid'5000 platform. As a PhD student,
+``ANR-11-LABX-01-01''). Computations have been performed on the Grid'5000
+platform and on the mésocentre of Franche-Comté. As a PhD student,
Mr. Ahmed Fanfakh, would like to thank the University of Babylon (Iraq) for
supporting his work.